Specifications

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(c) The interrupt sequence program of the host's CPU module can be started up
using the event issue function. This function reduces the response time of the
system and processes the real-time data receiving.
I50
CPU module
Transient transmission
from other station
Cyclic transmission
MELSECNET/H
Normal
sequence
program
Condition check
Interrupt condition
parameters
Relay information
Register data
Arrival at a channel
Network status
Conditions
matched
Interrupt
sequence
program
IRET
MAIN
END
Network module
(4) Expanded RAS functions
(a) By using the control station switch function, if the control station of the
network is down, a normal station is substituted for the control station,
enabling to continue the network communication.
(b) When a faulty station recovers and can resume the normal operation, it
automatically returns to the network to resume the data communication using
the automatic return function.
(c) The network stop time can be reduced because a control station that was
down can return to the network as a normal station by means of the
automatic return control.
(d) By using the loopback function (the optical loop system), it is possible to
continue the data transmission among operational stations by disconnecting
faulty areas such as a part of the network where there is a cable
disconnection, a faulty station, etc.
(e) By using the station detach function (coaxial bus system), even when some of
the connected stations are down due to power off, etc., the normal
communication can be continued among other operational stations.
(f) When an error occurs in a normal network due to disconnection, etc. the data
link can be continued by switching to the link data refresh on the standby
network if two network modules, a regular module and a standby module, are
installed for each PLC CPU (simple dual-structured network).
(g) The network module can continue the transient transmission even if an error
that stops the CPU module while the system is operating occurs.
(h) It is possible to check the time when a transient error occurred.
REMARK
The following faults make the RAS functions valid.
• Break in a cable
• Power-off of a slave station
• Network setting error
• Fault detectable by the self-diagnostics of CPU module
If the network module has become faulty, the RAS functions may not be activated
depending on the fault.